Dopamine is implicated in human diseases associated with social deficits, such as autism, and dopaminergic drugs are frequently used to treat symptoms of these diseases. However, very little is known about how dopamine may regulate social affiliation among mammals. The prairie vole is an ideal animal model for the neurobiological investigation of social affiliation because males and females form long-term pair bonds. Pair bonding is assessed by the partner preference test, a reliable behavioral index in which the subject spends preferentially more time with its familiar mate versus a conspecific stranger. This proposal will test the hypothesis that mating induced partner preferences are facilitated by dopamine released during mating. My preliminary experiments show that a non-specific dopamine receptor antagonist (either i.p. or microinjected into nucleus accumbens) blocked mating-induced partner preferences and a non-specific dopamine receptor agonist induced this behavior in the absence of mating. I propose to identify the dopamine receptor subtype in the nucleus accumbens that is important for pair bonding by using receptor specific drugs to manipulate partner preference formation. Since it is unlikely that dopamine acts at only one central location to influence pair bonding, I will then map the dopamine system in the male prairie vole and test if mating alters dopamine systems. Finally, I will examine if mating increases dopamine release in the nucleus accumbens. Together these studies will further our understanding of how dopamine is involved in mammalian social attachment.